82 GENERAL CHEMICAL AND PHYSICAL CHARACTERS. 



minutes, and in other animals only after 3 hours. In the case of blood 

 stains 6 to 60 days old, the older the stains the less resistance of the hemo- 

 globin, but the relationship between the different bloods remains that is, 

 the bands of human blood disappear sooner than those of dog's blood, 

 and those of dog's blood sooner than those of the others. Ziemke states 

 that in order to show differences in resistance to alkali the use of the spec- 

 trophotometer is not necessary, but that by colorimetric measurements 

 dried blood and blood stains of human blood can be distinguished from 

 those of domesticated animals, even though methemoglobin has been formed. 



IS THE OXYHEMOGLOBIN OF THE BLOOD OF ANY INDIVIDUAL A SINGLE 



SUBSTANCE? 



That there is always in the normal blood a mixture of oxyhemoglobin 

 and reduced hemoglobin in varying proportions has long been established, 

 but to what extent and constancy, if any, such substances as methemo- 

 globin, C0 2 -hemoglobin, and CO-hemoglobin may be present has not been 

 determined; nor has it been shown that either oxyhemoglobin or reduced 

 hemoglobin is a single homogeneous substance in any species of blood. 

 Hoppe-Seyler (Zeit. f. physiol. Chemie, 1878, n, 139) found that the oxy- 

 hemoglobin of the horse appears in the form of minute needles and prisms 

 which differ in solubility, which difference he believes may be due to dif- 

 ferent amounts of water of crystallization. Otto (Archiv f . ges. Physiologic, 

 1883, xxxi, 240), in repeating Hoppe-Seyler's experiments, also noted these 

 two forms, but he found that one form could not be separated from the 

 other by washing with dilute alcohol, as stated by Hoppe-Seyler. 



Bohr (Cornpt. rend. soc. biologie, 1891, cxi, 243), in his studies of the 

 homogeneity of hemoglobin, found that the portion of hemoglobin in the 

 mother-liquor after crystallization showed a lower combining power with 

 o\ym-ii than that which crystallized out; and in a previous article (Ceutral- 

 blatt f. Physiologie, 1890, iv, 242) he reported from the results of his experi- 

 ments that the oxyhomoglobin of the blood is not a simple substance, but 

 a mixture of oxyhemoglobins, and that there may exist in the blood four 

 forms, all giving the same oxyhemoglobin spectrum, but differing in their 

 absorption coefficients, in their percentages of iron (0.35 to 0.46), and in 

 their combining with () (0.4, 0.8, 1, and 2.7 c.c. O per gram). He believes 

 that there are also several forms of CO 2 -hemoglobin. 



Iliifner lAivhiv f. Anat. u. Physiologie, 1894, 130) seems, however, to 

 have demonstrated that Bohr's several forms of oxyhemoglobin were mix- 

 tures of oxyhemoglobin with varying amounts of methemoglobin and other 

 decomposition products which resulted from his methods of preparation. 

 Hiif net's suggestions are borne out by the investigations of Marchand 

 (Archiv f. path. Anat. u. Physiol., 1879, LXXVII, 488), and even by the 

 early work of Hoppe-Soyler and by the researches of others. In the blood 

 of cattle, Hlifner states, there is but one oxyhemoglobin, and likewise in 

 all the higher vertebrates. By the crystallographic method, however, we 

 have found several kinds of oxyhemoglobin in certain bloods. 



